This invention relates to an electrically charged spherical projectile and more particularly a hollow projectile having a ratio of surface area to mass greater than that of a solid body of a basic material to be charged.
Heretofore charged particle work in the field of electrostatics has been restricted to elemental particles or microparticles. It has been shown that large bodies can be charged in accordance with the laws of electrostatics. But applications of this science have been limited to generally areas such as electrostatic painting techniques, electrostatic separation of minerals, impactless printing, charge transfer as in xerography and dust and flue materials collection.
All of these applications have in common the charging or application of charges on small bodies. The dimensions of these bodies are typically particle mass=10.sup.-8 grams, particle charge=10.sup.-14 coulombs and particle radius=10 microns.
In the case of impactless printers the radius of the particles may get to be as high as 60 microns, and in the case of mineral separation, radii as large as 0.12 mm have been used.
From a theoretical viewpoint, all of the existing systems are based on following first order physics. More detailed analysis does not materially affect the conclusions. The charge on a particle is proportional to its surface area, and for a spherical particle, is related to the particle radius by EQU q=KR.sup.2
where:
q is the charge in coulombs PA1 K is a constant PA1 R is the radius of the particle in meters. PA1 V is the potential PA1 D is the distance between the plates PA1 m is the mass of the particle PA1 a is the acceleration of the particle PA1 F is the force acting on the particle ##EQU1## where K.sub.1 =(K/4/3.pi.), SG is the specific gravity of the round particles, and p.sub.w is the mass per unit volume for water at 4.degree. C. The acceleration can be written ##EQU2## where E is the average electric field intensity (V/D) between the plates.
The forces acting on the particle when it resides between two plates operated at potential difference V are: EQU F=qV/D=ma
where:
None of the previous applications, as described above, have used charged particles having a large mass but instead all of the particles are of dust or sand dimensions and smaller.